With that many failures, with the same brand, I think I would reconsider my choice of brands. A power supply is not some place to try to save money on. They can fail and ruin your entire system. Although they cost more, I always recommend quality brands such as Corsair, Seasonic and Antec. Those are top of the line PSU's. The only other issue is the size of the unit. If you buy too small of a power supply, the computer is demanding more of it, than the power supply is capable of. Find some good power supply calculators and see how much your computer needs, then add about 20%-25% to it to allow for upgrades. It will also make your power supply not be strained, run cooler and last longer.